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Detection of cytomegalovirus resistance to antivirals in paediatric haematopoietic stem cell transplant recipients: study in a paediatric cohort in the Czech Republic

Abstract number: P1768

Hubacek P., Boutolleau D., Hrdlickova A., Conan F., Zajac M., Keslova P., Formankova R., Agut H., Sedlacek P.

Objectives: Despite the improvement of infection monitoring and antiviral treatments, cytomegalovirus (CMV) infections remain a major cause of morbidity and mortality in allogeneic haematopoietic stem cell transplant (alloHSCT) recipients. CMV resistance to antivirals, which is one reason for treatment failure, was investigated in a paediatric population.

Methods: Between 2002 and 2008, 6339 whole blood samples (median: 30/patient) from 192 alloHSCT patients (median age at HSCT: 8.9 yrs) were tested. After DNA extraction, CMV genome and albumin gene were quantified using real-time quantitative PCR, and results were expressed as normalised viral copies (NVCs) per 100000 human genome equivalents. First-line antiviral treatment, usually ganciclovir (GCV), was initiated when CMV load exceeded 1000 NVCs, and switched to foscarnet or cidofovir in case of none response or clinical signs of CMV infection. If clinical resistance was suspected, based on the absence of viral response after 2 weeks of a well-conducted treatment, CMV resistance was studied by restriction analysis and sequencing of UL97 phosphotransferase and UL54 DNA polymerase genes.

Results: CMV load was over 100 NVCs in 839 samples from 86 patients (45%), over 1000 NVCs in 346 samples from 55 patients (29%) and 10000 NVCs in 87 samples from 20 patients (10%). Despite treatments, mild signs of CMV infection developed in 22 patients (11%), and CMV disease was observed in 8 patients (4%; 6 pneumonias, encephalitis and colitis). Seven patients died in consequence of CMV infection.

Among the 22 patients (11%) with suspicion of resistance, genotypic resistance of CMV was evidenced in 4 patients (7%), with median of 273 days post-alloHSCT and CMV load of 10277 NVCs. Resistance to GCV was associated with mutations L595S and A591V in UL97, del981–982, N408K, V715M and P522S in UL54. Natural polymorphisms in UL54 were detected in 16 patients (8%). Four novel changes of unknown phenotype in UL97 and 6 in UL54 were detected. The detection of GCV resistance of CMV led to the switch of the treatment in 4 patients, with success in 3.

Conclusions: CMV load normalisation is useful for the surveillance and the treatment of CMV infection after alloHSCT. Genotypic testing of CMV resistance proved to be important in case of clinical resistance. Further studies are required to ascertain the true nature of the novel mutations within UL97 and UL54 genes appearing after prolonged antiviral treatments.

Supported by VZ FNM642003, MSTM0021620813, NR9418–3

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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